Field of the Invention
The invention relates to a smart card comprising a plastic card body with a semiconductor chip that is mechanically fastened and that is contacted by means of a leadframe. The leadframe constitutes electrical contacts for contacting from the outside, ensures the electrical contact with the chip, and it is formed, in the region of the electrical contacts, in the form of contact tabs.
A general problem in the production of smart cards with a leadframe is the permanent and operationally reliable connection between the chip, the chip module containing the leadframe or the leadframe and the plastic card body on the other side. The chip itself is generally bonded into a recess within the plastic card body. Reinforcing elements are incorporated in the plastic card body, which is, for example, bent in operation. The placing of the electrical contacts in relation to the chip may be different. In is thereby possible, for example, for a so-called chip module to have a stiffness which prevents damage to the chip and to the contacts which are present on the chip module. If, however, the electrical contacts are arranged relatively far away to the outside from the chip, problems result because of a lack of bending strength or tensile strength of contact tabs at the connecting points in the region of the electrical contacts. Furthermore, faults can occur in adhesive connections as a result of the critical reaction mechanism of adhesives which harden at different speeds. Furthermore, the adhesive connections can age or embrittle. Bending up and sticking up of the edges of a leadfeame in the outer region could thus occur.
Prior art smart cards are constructed, for example, by means of bonding a basic element over the complete area using rapidly reacting adhesives or by corresponding stamping.
German Patent application No. P 195 27 331.1, for example, describes a smart card with a plastic card body in which a semiconductor chip is placed. The semiconductor chip is electrically connected to a leadframe which forms contact tabs that are at least in partial contact with a plastic body surrounding the semiconductor chip. In the vicinity of the plastic body, the contact tabs have a flexible region. This form of the arrangement of semiconductor chip and electrical contacts in the basic card body does not ensure that bending of the smart card does not lead to permanent deformations at the contacts (lead-frame), with the result that the ends of the contact tabs could stick up.
German patent DE 44 41 931 C1 describes a smart card with a semiconductor chip and a plastic card body housing the chip. The chip is mechanically fastened in the plastic card body and can be contacted electrically from the outside via electrical contacts. The electrical contacts are part of a lead frame which are contacted with the semiconductor chip. The leadframe has contact tabs towards the outside. The contact tabs run parallel at the surface of the large-area side of the smart card. The contact tabs end at the area provided for contacting.